How do you LIGHT Up your world ?

Virginia SOL 5.3

Part II-Examining Light

with Hands-On Activities

Compiled by, Marjorie Anne Wallace

Elementary Science Resource Teacher

2002-2005, NNPS & NSF Coop Agreement

Welcome to a power point presentation on LIGHT.

• We will investigate the following:• 1. What is light?• 2. What makes up the visible spectrum?• 3.How does a prism work?

• 4.Are there any hands-on/minds-on activities I can do to learn more?

LIGHT Standards• National Science

Education Standards• Physical Science:

Content Standard B• As a result of the

activities in grades

K-4, all students should develop an understanding of light, heat, electricity, and magnetism.

• Virginia Standards of Learning 5.3a-e:

• The student will investigate and understand basic characteristics of visible light and how it behaves.

• (*Key concepts, 5.3a-e, are listed in your teacher curriculum guide)

A light review:• Our primary source of light is the sun.• Light travels in straight lines at a speed of

186,000miles per second.• Light waves travel faster than sound waves.• Light energy from the sun travels through space ,

reaches earth, and some of it turns to heat energy and warms the earth’s air.

• Light from the sun also travels to the cells of green plants (producers) and is stored as energy.

• When light reaches an object, it is absorbed, reflected, or passes through it.

Sensing Light• Humans have two

light detectors.• Do you know what

they are called?

Did you realize cameras and camcorders are light detectors too?

SOL query5th grade 2003 Released Test Item#31 / CORE 1

#31 By passing white light through a prism, you can tell-

– A that white light is actually a mixture of different colors

– B the mass of the prism– C the original source of the light– D that blue light is brighter than white

light

What is light really?Electromagnetic radiation waves

• Light waves are three dimensional

• Light waves vibrate in all planes around a center line.

• The waves have high points called “crests.”

• Waves also have low points called “troughs.”

• *The distance from one crest to the next crest is called a “wavelength.”

• *The number of waves passing a given point in one second is called the “frequency.”

wavelength

*A Science Museum of VA:Light Science Activity

*Electromagnetic Radiation• Electromagnetic radiation can be described in terms of a

stream of photons. Each photon is traveling in a wave-like pattern, moving at the speed of light and carrying some amount of energy.

• The only difference amongst radio waves, visible light, and gamma-rays is the amount of energy of the photons. Radio waves have photons with low energies. Microwaves have a little more energy than radio waves. Infrared has still more energy.

• As we move down the chart we see visible, ultraviolet, X-rays, and gamma-rays whose photon energies gradually increase.

• Gamma and Cosmic rays have the highest energy waves.

*Slide info from NSTA 2004 conference

Remember radio waves are long…and gamma rays are small

Radio-TV -Microwave- Infrared - VISIBLE -Ultraviolet -X-rays - Gamma- Cosmic

Radio(Longest electromagnetic waves)

• Emitted by– Astronomical Objects– Radio Station

Transmitters

• Detected by– Ground based radio

telescopes– *If you turn on a radio,, it

will convert the radio wave energy into sound energy.

Television• Shorter than radio,

also used to carry messages (pictures & sound) to our TV sets.

• *We can sense the TV waves around us with our televisions.

Microwave

• Emitted by:– Gas clouds collapsing

into stars– Microwave Ovens– Radar Stations– Cell Phones

• Detected by– Microwave Telescopes– Food (heated)– Cell phones– Radar (systems)

Infrared(Heat or Thermal)

Are you a source of infrared? YES you are!

• Emitted by– Sun and stars (Near)– TV Remote Controls– Food Warming Lights

(Thermal)– *Everything at room

temperature or above,=HEAT

• Detected by– Infrared Cameras– TVs, VCRs,– Your skin

Let’s take a look at Herschel’s Experiment

• Herschel’s Experiment– Discovered Invisible

Light– In 1800, Herschel

places his control thermometer just outside the red end of the spectrum

– Result: The outside thermometer registered the highest temperature

Let’s set up Herschel’s Experiment

• Set up of Box Design for Conducting the Herschel Experiment.

Conducting Hershel’s Experiment• Place a sheet of white paper

inside a cardboard box• Tape three thermometers

together and place inside box

• Cut a small notch in the top of the box and position a glass prism so that the spectrum is projected inside the box

• Arrange the thermometers so that one is just outside the red end of the spectrum, with no visible light falling on it

VisibleEach color is a different size wave.

Red the longest & violet the shortest• Emitted by

– The sun and other astronomical objects

– Laser pointers– Light bulbs

• Detected by– Cameras

(film or digital)– Human eyes– Plants (red light)– Telescopes

Prism Power: Roy G. Biv Activity

• *What happens when light shines through prisms?

• Materials :prism, PASCO “wave it,”equipment, paper, +7 Roy G. Biv crayon colors,

• 1. Give handouts. Darken the room and turn on light source. What color is the light? If I use a prism can you predict what will happen to the light?

• 2.Now use the prism. What color is the light?• 3. Color in your hand out to match the spectrum.

*PASCO Probe Activity OR *AIMS:Primarily Physics: Prism Power Activity

UltravioletSunburn / black light

• Emitted by– Tanning booths (A)– The sun (A)– Black light bulbs (B)– UV lamps

• Detected by– Space based UV

detectors– UV Cameras– Flying insects (flies)

X-ray• Emitted by

– Astronomical objects – X-ray machines– CAT scan machines– Older televisions– Radioactive minerals– Airport luggage

scanners

• Detected by– Space based X-ray

detectors– X-ray film– CCD detectors

Chandra X-ray Observatory

• Chandra is designed to observe X-rays from high energy regions of the universe, such as the remnants of exploded stars.

• The most sophisticated observatory built to date.

• Deployed by the Space Shuttle Columbia on July 23, 1999,

Chandra X-ray Observatory

*Slide from 2004 NSTA Conference

Gamma Ray(Short electromagnetic waves but more energetic)

• Emitted by– Radioactive materials– Exploding nuclear

weapons– Gamma-ray bursts– Solar flares

• Detected by• --Geiger counters

– Gamma detectors and astronomical satellites

– Medical imaging detectors

Sources of g-ray Emission• Black holes• Active Galaxies• Pulsars• Diffuse emission• Supernovae• Gamma-ray bursts• Unidentified

COSMIC Rays(The highest energy waves and the deadliest)

• Cosmic rays come from deep space and can pass through the Earth.

• A great question!• Radio waves= (Buildings to human size);• Microwaves

(Humans-beetles);• Infrared waves (Eye of a needle);Visible waves (microscopic size)!

WOW! All the rest are the size of molecules, atoms, atomic nuclei and smaller..

Part III looks at: reflection and refraction of LIGHT.Part I examines: what is light? Waves, opaque, transparent, & translucent, & sources of light around us.Special thanks to NSTA Conference 2004 workshops on light!